"The story began in 1976, when Zecharia Sitchin wrote "The Twelfth Planet," a book which used Stitchin's own unique translation of Sumerian cuneiform to identify a planet, Nibiru, orbiting the sun every 3,600 years. Several years later, Nancy Lieder, a self-described psychic, announced that the aliens she claimed to channel had warned her this planet would collide with Earth in 2003."
https://www.space.com/15551-nibiru.html
"Most believers say that Nibiru is a mysterious planet that orbits the sun, completing a new trip around the star every 3,600 Earth years. And supposedly, Nibiru is on a collision course with us. The story goes that Nibiru will someday crash into our home world or, failing that, get close enough to trigger a mass outbreak of natural disasters that'll end human civilization as we know it."
https://science.howstuffworks.com/nibiru.htm
"Nibiru (also known as Planet Nine or Planet X) is prophesised to collide with Earth and destroy all of humanity, but is its existence pseudoscience or is there any proof?"
https://www.sciencefocus.com/space/what-evidence-is-there-for-the-existence-of-the-planet-nibiru/
"Of the 300+ Anunnaki who stayed on Earth, the majority of them (around 200) are loyal to Marduk, and some are still loyal to the Kingdom (Nibiru)."
https://www.mazzastick.com/marduk-issue-earth-bound-anunnaki/
"Caltech researchers have found mathematical evidence suggesting there may be a "Planet X" deep in the solar system. This hypothetical Neptune-sized planet orbits our Sun in a highly elongated orbit far beyond Pluto. The object, which the researchers have nicknamed "Planet Nine," could have a mass about 10 times that of Earth and orbit about 20 times farther from the Sun on average than Neptune. It may take between 10,000 and 20,000 Earth years to make one full orbit around the Sun."
https://solarsystem.nasa.gov/planets/hypothetical-planet-x/in-depth/
Astronomers say a Neptune-sized planet lurks beyond Pluto
https://www.sciencemag.org/news/2016/01/astronomers-say-neptune-sized-planet-lurks-beyond-pluto
Is There a Giant Planet Lurking Beyond Pluto?
https://spectrum.ieee.org/aerospace/satellites/is-there-a-giant-planet-lurking-beyond-pluto